Identification and partial purification of fibroblast growth factor from the brains of developing rats and leucodystrophic mutant mice.

High titres of fibroblast growth factor activity (assessed by mitogenicity for Balb/c 3T3 fibroblast cells in vitro) have been extracted from the brains of foetal and neonatal rats long before myelinogenesis commences, from the brains of hypomyelinated, leucodystrophic, murine mutants and from normal adult rats. Partial purification, by ion-exchange chromatography and gel filtration, indicates that the brain fibroblast growth factor activity from these sources is associated with very similar basic protein fractions. These results, together with the observation that none of the samples of partially purified basic fibroblast growth factor elicits the experimental allergic encephalomyelitis response attributed to myelin basic protein in the rat, suggest that basic fibroblast growth factor is not a degradation product of myelin basic protein.